IEC 62304 is the international standard for medical device software lifecycle processes. It mandates planning, design controls, risk management, traceability, testing, validation, and post-market surveillance. The standard ensures medical device software is safe, effective, and traceable from requirement to deployment. Practitioners apply IEC 62304 across the full development lifecycle: risk analysis (what can go wrong?), design specification (how will it work?), code review (are requirements met?), testing (does it work?), and validation (does it work in the real world?). Every step is documented, traced, and auditable for FDA or European regulatory inspections.